Various types of automatic ice making machines for continually making various shapes of ice cakes including cubes and plates in large quantities are suitably utilized depending upon the applications required. For example, popular ice making machines include:
(1) so-called closed cell system ice making machines having a multiplicity of freezing cells opening downwardly and formed within a freezing chamber, within which the freezing cells can be separably closed by means of a water tray, and water for freezing is injected into the freezing cells through means of the water tray so as to gradually form ice cubes therein;
(2) so-called open cell system ice making machines having a multiplicity of freezing cells opening downwardly, within which water to be frozen is directly injected into the freezing cells in the absence of a water tray so as to form ice cubes the freezing cells; and
(3) flow-down system ice making machines having a tilted freezing plate, within which water to be frozen is supplied so as to flow upon the upper or lower surface of the freezing plate so as to form an ice plate upon the corresponding surface.
According to any one of these freezing systems, the automatic ice making machine generally has an ice making unit for making ice cakes disposed at an upper position of the housing of the machine, and an ice reservoir disposed below the ice making unit, so that the ice cakes formed in the ice making unit may gradually be accumulated within the ice reservoir. However, such types of ice making machines having an integral structure of the ice making unit and the ice reservoir sometimes are not satisfactory for large-scaled shops where ice demand increases greatly depending upon the time zone and season or for consumers who use large amounts of ice cakes. In such cases, stack-on type ice making machines can be suitably used. The stack-on type ice making machine comprises an ice making unit 12 having an ice making mechanism 10 and a freezer (not shown), and an ice reservoir 14, as shown in FIG. 4, which are formed separately as independent mechanical units, such that the ice making unit 12 can be combined with an ice reservoir 14 having a desired level of capacity and can be stacked upon the latter ice reservoir 14.
In such stack-on type ice making machines, a guide plate 16 is disposed in an inclined manner below the ice making mechanism 10, and an opening 18 is formed within the bottom wall 12a of the unit 12 at a position beneath the lower end of the inclined guide plate 16, whereby the ice cakes formed within the ice making mechanism 10 slide along the guide plate 16, after they are released, and into the ice reservoir 14 through means of the opening 18, so as to be stored therein. Furthermore, a means 20 for detecting when the ice cakes reach a predetermined level (so-called ice fullness detector) is disposed within the ice reservoir 14. The detector 20 is designed to detect the fullness of the ice reservoir 14 with respect to the accumulation of the ice cakes and stop the operation of the ice making machine.
The following arrangements of the ice fullness detector 20 are known. For example, as shown in FIG. 4, a predetermined length of detector member 22 is fixed so as to extend downwardly from the bottom wall 12a of unit 12 at a position adjacent to the opening 18 defined within the bottom wall 12a of the ice making unit 12, and the ice fullness detector 20 includes a temperature element 20a which is attached to the lower end of the detector member 22 such that the temperature element 20a is disposed at the tip thereof. Accordingly, when the level of the ice cakes being accumulated within the ice reservoir 14 increases after an operation of the ice making machine for some period of time, the uppermost ice cakes contact the temperature element 20a. Thus, the detector detects the fullness of the ice reservoir 14 with the accumulation of ice cakes and stops the operation of the ice making machine. Alternatively as shown in FIG. 5, a detector member 22 is fixed upon the internal wall surface of the ice reservoir 14 so as to protrude inwardly therefrom, and the temperature element 20a is attached to the tip of the detector member 22. Incidentally, since the ice cakes being accumulated within the ice reservoir 14 assume a heap having its apex immediately below the opening 18, the temperature element 20a of the ice fullness detector 20 is disposed so as to be adjacent to the opening 18.
As another arrangement, as shown in FIG. 6, a cavity 24 opening downwardly is defined within bottom section of the ice making unit 12, and also a through hole 26 is formed within a side wall of unit 12 adjacent the guide plate 16, and opening into the cavity, so as to allow passage of the ice cakes sliding downwardly along the guide plate 16. A detecting member 22 is also fixed upon the opposite wall of this cavity 24, or upon the side wall opposing disposed opposite the through hole 26, and the temperature element 20a of the ice fullness detector 20 is disposed at the free end of the detecting member 22. In the last mentioned case, the temperature element 20a detects the fullness of the ice reservoir 14 when the ice cakes having been made within the ice making mechanism 10 fills the cavity 24 after filling the ice reservoir 14.
As described above, while the ice fullness detector 20 is fixed to the ice making unit 12 or to the ice reservoir 14, actual mounting of the detector 20 involves many difficulties since it is mounted in a predetermined state or position corresponding to the relatively aligned disposition of the unit 12 and reservoir 14 when the ice making unit 12 is stacked upon the ice reservoir 14. To describe such in detail, in the structures as shown in FIGS. 4 and 5, in order to properly affix the detector 20 upon or within the ice making machine, the operator must remove a cover (not shown) disposed upon the top of the ice making unit 12, and put his hands through the upper opening of the ice making unit 12 and through the small opening 18 so as to fix the detecting member 22 having the ice fullness detector 20 disposed thereon onto the internal wall surface of the ice reservoir 14 or upon the lower surface of the bottom wall 12a of the ice making unit 12. Thus, the above structures involve a problem of greatly reducing the operational efficiency. Moreover, the required installation operation within the limited space forces the operator to assume a difficult position, and consequently ice fullness detectors 20 often cannot be disposed correctly in position. As a result of such inaccurate disposition of the detector 20, the detector 20 fails to correctly detect the fullness of the ice reservoir 14 at the proper time even when more than the predetermined amount of ice cakes are accumulated therein and the ice cakes often overflow the ice reservoir 14 so as to reach the ice making mechanism 10 and thereby cause damage to the ice making mechanism 10.
Furthermore, in connection with the inspection and maintenance of the ice making machine, while the ice fullness detector 20 must be removed when the ice making unit 12 is separated from the ice reservoir 14, this removal requires intricate handling. It can also be pointed out that the arrangement shown in FIG. 5 involves a problem in that the ice fullness detector 20 can be damaged, since the detector 20 is disposed toward the inside of the ice reservoir 14 if the ice making unit 12 is separated from reservoir 14 without removing the ice fullness detector 20 therefrom.
In the arrangement shown in FIG. 6, the cavity 24 defined within the ice making unit 12 should be designed to have dimensions such that it can allow the smooth passage of the group of ice cakes made during one cycle of operation of the ice making mechanism 10. In determining the capacity of the cavity 24, if it is allowed to have a sufficiently large capacity, then the entire ice making unit tends to be disadvantageously larger.